{{define "template.html"}}
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h1>Hello {{index . "name"}}</h1>

<p>{{ with $x := index . "reverse" }}
    {{ call $x "foobar" }} &lt;-- this will call the $x with parameter "foobar"
    {{ end }}
</p>
</body>
</html>
{{end}}